Retrievable plug and actuating means therefor



G. S. KNOX March 6, 1956 RETRIEVABLE PLUG AND ACTUATING MEANS THEREFOR Filed Dec. 22, 1952 3 Sheets-Sheet 1 GQANV/LLE 5. KNOX,

INVENTOR.

BY 3% "vSQ ATTORNEYS.

March 6, 1956 e. s. KNOX 2,737,245

RETRIEVABLE PLUG AND ACTUATING MEANS THEREFOR Filed Dec. 22, 1952 3 Sheets-Sheet 2 ArmeA/EYs,

United States PatentO RETRIEVABLE PLUG AND ACTUATING MEANS THEREFOR Granville S. Knox, Glendale, Califl, assigner to Hydril Company, Los Angeles, Calif., a corporation of Ohio Application December 22, 1952, Serial No. 327,278

10 Claims. (Cl. 166125) This invention has to do generally with plugs and their actuating means for use in connection with strings of oil well pipe, and is more particularly concerned with such plugs and means wherein the plugs are adapted to be set within well tubing to form a temporary barrier in the tube bore and then, when the occasion arises, adapted to be bodily retrieved.

The points at which such plugs are often set are many thousands of feet from the ground surface and, of course, are beyond the powers of the operator to observe. Yet it is necessary that the plugs be capable of being quickly and positively set in the landing shoe of the tubing and the setting tool be then easily released. It is just as necessary that they be capable of quick and positive removal when the tubing is to be unplugged.

When it is realized that the setting and retrieving is to be accomplished by a long, flexible lowering or measuring line, it will be seen that the difiiculties of insuring positive and rapid action are enhanced, and it is among the objects of the present invention to overcome these difficulties.

It is also among the objects of the invention to provide a simple, durable device, and one in which the likelihood of fouling or of becoming sanded up are reduced to a minimum, and, of course, a plug which, when set, is adapted to insure a complete seal-ofi of the tubing bore.

One of the principal objects of the invention is to provide a mechanism whereby, during the retrieving operation, the danger of breaking the retrieving line is reduced to a minimum. This is accomplished by so fashioning the locking mechanism of the plug and the retrieving mechanism, that the retrieving mechanism cannot be latched to the plug until the plug lock has been released. That is, the retrieving mechanism, when it meets the plug, starts its plug-unlocking functions, but, if it is lifted before the plug is unlocked, it pulls free of the plug, and the retrieving operation must be started again. In previous plugs it was possible to latch the retrieving tool to the plug before the plug was unlocked from the landing shoe, and, as a result, if an upward pull were exerted on the line, in the mistaken belief that the plug was unlocked, the retrieving line was subjected to rupturing strains.

Other objects and features of the invention will be made apparent in the following detailed description, reference being made to the accompanying drawings, in which:

Fig. 1 is an elevation of the plug and setting tool as they appear when latched together in preparation to being lowered through a tubing,

Fig. 2 is an enlarged medial section through the latchedtogether plug and setting tool as they appear when being lowered into a landing shoe,

Fig. 3 is a section on line 33 of Fig. 2,

Fig. 4 is an enlarged section on line 44 of Fig. 2,

Fig. 5 is an enlarged, fragmentary section showing the 'latch between the setting tool and the plug,

further advanced in the setting operation,

Fig. 7 is a view similar to Fig. 6, but showing the plug fully set or landed and the setting tool removed,

Fig. 8 is an enlarged, fragmentary detail of the sealing unit of the plug,

Fig. 9 is a fragmentary section on line 99 of Fig. 8,

Fig. 10 is an elevation, partly in broken away section of the retrieving tool as it is lowered through the tubing,

Fig. 11 is a section on line 1111 of Fig. 10,

Fig. 12 is a detail section on line 1212 of Fig. 10,

Fig. 13 is a view similar to Fig. 7, but showing the retrieving tool being lowered into operative association therewith,

Fig. 14 is an enlarged, fragmentary section showing the position of the parts at the instant the retrieving tool engages the locking plunger, which is a position slightly advanced beyond the position illustrated in Fig. 13; and

Fig. 15 is a view similar to Fig. 13, but showing the retrieving tool fully engaged with the plug.

I have illustrated at A a string of oil well tubing to which is coupled at B a landing shoe C. The novel plug is indicated at D, the setting tool at E and the retrieving tool at F.

Shoe C has a major bore 10 which flares at its upper end to provide a conical shoulder 11. The bore is centrally enlarged to provide an annular groove 12 whose upper and lower defining faces 13 and 14, respectively, are in the form of oppositely facing conical shoulders. The lower part of the shoe has a reduced-diameter portion 15 adapted to receive the packer of the plug, the ultimate seal being accomplished in this zone of the shoe. At the junction of bores 10, 15, there is provided a conical seating shoulder 16.

Plug D is made up generally of a barrel 17 comprising an upper section 18, a lower section or cage 19, an intermediate section 20, all these sections being tubular in character, and a packer P. Sections 18 and 20 are coupled by threads 21 (Fig. 7) while cage 19 is threaded at 22 on the lower, stem-portion or neck 23 of section 26, forming a retention member holding packer P against dropping from the stem portion.

The upper portion 24 of barrel 17 (which upper portion is made up of section 18 and the upper end of section 20) is of an outside diameter to be taken, with ample clearance, in shoe-bore 10, while portion 25 of section 20 is of reduced diameter and is adapted to have nice sliding fit within shoe-bore 15. The conical shoulder 26 is complementary to landing seat or shoulder 16 of the shoe. Cage 19, which has considerable annular clearance within bore 15, cages a valve ball 27 which, is normally pressed by spring 29 against seat 28 at the end of neck 23, the spring being bottomed on the annular cageshoulder 30. The valve ball is thus adapted to stopper the lower end of the plug bore against well-pressure from below, but to allow predominant pressure from above to open the plug bore for free downward flow therethrough under circumstances to be mentioned later.

Packer P (Figs. 7, 8, and 9) comprises, in preferred though not limitative embodiment, an annulus 31 of natural or synthetic rubber molded to rigid ring 32, the rubber having integral, headed key-plugs 33 molded into complementary sockets 34 in the ring. The under face of the ring has an annular groove 35 which is a V-crosssection and takes a complementary portion of the rubber ring. The rubber seal ring 31 has a downwardly facing groove 36 which is of conical cross-section and is adapted to receive the annular vertical flange 37 on retention ring 38, this ring being limited as to upward movement by the annular shoulder 39 (Fig. 8) on section 23. On the other hand, ring 38 is limited to slight downward movement by the upper end 40 of cage 19. Upward movement, of ring 32 is limited by the downwardly facing shoulder 41 of section 20.

Packing rubber 31 is of an outside diameter initially to fit shoe-bore 15 snugly and when the plug is seated (Fig. 7) well pressure from below enters groove 36 and, in its tendency to spread ring tongues 42, forces the rubber 31 (Fig. 8) tightly against shoe C and barrel section 20, thus, with valve ball 27, preventing upward wellfiow past the plug. Flange 3'7 prevents tongues $2. from being accidentally folded .in prior to the application of fluid pressure there-against.

Bore 43 of section 2% opens to larger bore 44 of section 13, but is also provided with cross-vents &5, just below shoulder 26, to relieve pressure differentials as portion 25 enters bore 15.

A locking sleeve or tubular plunger 46 is mounted for limited vertical reciprocation in bore 44, the sleeve having a camming head 47 which is slightly conical (Fig. 14), that is, its outer peripheral face slightly tapers inwardly and upwardly. The lower end of the head is square-cut to form an annular shoulder 48, while the upper end of the head is cut to provide an annular shoulder 4-9 which may be arcuate in cross section, the radius of curvature being approximately equal to the radius of one of the lock-balls or detents a, which will be later described.

An annular flange 51, spaced below the upper end 52 of sleeve 46, serves a dual purpose. First, it is adapted to engage the downwardly facing shoulder 53 on section 18 to limit the upward movement of sleeve 46 under the influence of spring 54 which is contained within bore 44 of section 18 and is bottomed on shoulder 55. The flange 51 also defines the upper end of annular groove 56 of sleeve 46, the lower end of which groove is defined by shoulder 49, the groove serving a purpose to be explained.

Cut through the wall of section 18 are a plurality of equi-angularly spaced radial ways 57 (Fig. 4) which receive a like number of locking balls or detents 50. The diameter of each of these balls is slightly greater than is the length of a way 57, so when sleeve 46 is urged upwardly to its upper limit of travel by spring 54- (Fig. 2) in which position sleeve-head 47 closes, in effect, the inner ends of the ways, the balls project somewhat beyond the peripheral face of section 18. To prevent further outward radial movement of the balls, the ends of the ways are slightly peened, as at 58. Thus, as long as sleeve 46 is spring-held in the position of Fig. 2, head 47 holds balls 50 in their positions of fullest radial projection.

Shoulder 53 is formed by the lower face of flange 59, the upper end of sleeve 46 being annularly cleared from said flange and, in the position of Fig. 2, extending above that flange. Drain holes 60 prevent the pocketing of sand above flange 51. The portion 61 of the bore of section 18 is of enlarged diameter, this portion terminating at its upper end in an upwardly and inwardly inclining, annular latch shoulder 62 (see Fig.5) leading to a slightly smaller-diameter bore portion 63. A conical counterbore at the upper end of section 18 provides an annular, downwardly and inwardly inclining shoulder 64.

The setting tool E comprises a generally cylindrical body portion 65 which has a threaded socket 66 to take the threaded stud 67 of the axial, cylindrical shank 68 which terminates in a downwardly pointing, conical head 69. The body portion and head preferably have wrench flats 70 and 71, respectively. Clamped between the opposed shoulders 72 and 73 of portion 65 and shank 68, respectively, ,is a ring '74 which has integral, depending, spring latch fingers 75 which are arcuate as viewed in plan section (Fig. 3) and are capable of being sprung radially inward from the positions of Fig. 5. Each finger has a long, spring-shank portion 76 and a terminal head 77 provided with a downwardly and outwardly inclined latching shoulder 78, complementary to shoulder 62, and an inwardly and downwardly inclined shoulder '79.

Preferably, weight, is added between the ,loweringline '79 and plug D to insure sufficient .weightjo .seatthe plug properly in shoe C. For this purpose, either or both dead weight in the form or" a sinker bar or live weight in the form of jars, may be provided, but since these elements are not essentials to my invention, l have shown conventionally only a sinker bar 89. The sinker bar, attached in the usual manner to cable 79, is coupled at 81 to the body portion 65 of setting tool F.

Shoe C is, of course, deep within tubing A, while the setting tool E is releasably latched to the plug D at the ground surface in preparation for a plugging operation. This latching is accomplished by telescoping tool E within the bore of the plug, fingers 75 being cammed inward as they pass through bore portion 63 and then springing outwardly to engage shoulders 73 with shoulders 62, the load of the plug thus being transferred to line 79. Preferably, though not necessarily, when these shoulders are in engagement, setting head 69 engages end 52 of sleeve 46 (Fig. 5).

The attached setting tool and plug are then lowered down to shoe C, all parts being in the positions of Figs. 2 to 4 until balls 50 engage shoe-shoulder 11, it being understood that the angles of shoulders 62 and "1'8 are such, and the spring-strength of fingers 75 is such, that the mere weight of the plug will not cam the fingers into release position, but will allow said fingers to be easily cam-released when the plug is subsequently locked in the shoe.

Fig. 2 illustrates the position of the parts just before shoulder ll is engaged by balls 59. As soon as thatengagement occurs, barrel 17 will be checked in its descent, but setting tool E and sleeve 46 will continue downward, compressing spring 54 and bringing groove 56 into alinement with loclc-ballsfil). Shoe shoulder 11 will then cam balls 50 into said groove, and tr e plug D will thus be freed for bodily descent, Fig. 6 illustrating the position of parts after this movement starts but before the plug is bottomed in the shoe. It will be noted that balls 50 now occupy positions wherein barrel l7 and sleeve 46 ,are locked by balls 50 against eifective relative axial movement.

The downward movement of tool E and the plug then continues until plug shoulder 26 engages shoe shoulder 16, meaning that packer P is in operative position within shoe-bore 15. By this time, balls 5% will be in line with groove 12. Then measuring line and setting tool are pulled upwardly, the upward pressure of spring 54 causing sleeve 46 to follow the head 69 until said sleeve again reaches the position, with respect to barrel 17, of Figs. 2 and 5. During upward movement of the sleeve, head 47 urges balls 56 radially outward and into the groove 12. Thereafter, until a retrieving tool is introduced, head 47 will be spring-held in a position to prevent inward movement of balls 56 (Fig. 7) and thus plug D will be positively locked by those balls to shoe C, except for the slight axial movement represented by the lost-motion extent of groove 12. However, this slight capacity for movement is not suflicient to allow packer P tobe lifted clear of bore 15.

The operator continues the up-haul on line 79, with the result that fingers 75 are camrned radially inward by shoulder 62 to unlatch the tool E from the plug, and the'tool is withdrawn from the tubing.

The plug is now releasably locked in the fully landed and "set position of Fig. 7, whereafter said plug, with its packer P and valve 27, presents a barrier which isolates the bore of the tubing above the plug from pressurized well-fluid beneath the plug.

When it is desired to retrieve the plug, the fluid pressures above and below the plug are first equalized in order to prevent the measuring line, by which the retrieving tool is handled, from becoming fouled because of sudden and rapid upward movement of the plug resulting from excessive pressure below the plug, as might ntherwise v.nccur as n as the plug is unlocked fr m shoe C. This .equalizatiouis accomplished by oil or water into the tubing above the plug, any excess fluid so supplied forcing check valve 27 open and thus passing harmlessly to the tubing below the plug.

Retrieving tool F (Fig. 10) is generally in the form of a dart applied to measuring line 79. As in the case of setting tool E, a sinker bar and jars are preferably coupled between the measuring line and tool, though only a sinker bar 80 is here shown. The sinker bar insures ample weight for accomplishing the unlocking of the plug, and the jars, if present, can be used to hasten the dislodgment of the plug from shoe C in the event sand or other foreign matter has become packed between the two.

Retriever F comprises a body portion 85 coupled at 86 to sinker bar 80, and a coaxial plunger portion 87, the two being threadably connected at 88. The body portion is provided with vertically extending centering or guide fins 89 which are end-tapered as at 90 (Fig. 11). Plunger portion 87 includes upper and lower stem-sections 91 and 92, respectively, the section 92 being of slightly greater diameter than section 91 and thus forming an upwardly facing shoulder at 93. At the lower end of section 92 is a head 94 having an upwardly and inwardly tapering conical portion 95 and an oppositely tapering, terminal portion 96.

Slidably mounted on stem portion 91 is a ring 97 from which depend the spring fingers or latches 98, which, as shown in Fig. 12, are arcuate in plan-section. The lower ends of fingers 98 carry latching heads 99 having upwardly facing, tapered shoulders 100, which are complementary to shoe-shoulders 62, and downwardly and inwardly tapered tips 101. Spring 102 on stem portion 91 normally holds collar 97 against shoulder 93, in which position latch heads 99 are at the lower extremity of head cone 95, the diameter of the cone at this point being such that the lower ends of the spring fingers 98 are sprung outwardly at least to the extent that the effective outside diameter of the ring of heads 99 is equal to barrel-bore 61.

Accordingly, when tool F is lowered through tubing A to the plug, with head 94 entering the upper end of barrel 17, the lower ends 100 of finger-heads 99 will engage barrel-shoulder 64 and temporarily check the descent of the fingers and hence of collar 97. This, of course, compresses spring 102 and brings lesser-diameter portions of cone 95 into the plane of finger-heads 99. Consequently, the spring fingers move gradually inward, with barrel shoulder 64 finally camrning the heads inwardly far enough to pass into bore-portion 63 of barrel-section 18 to the position of Fig. 13. In this position, head-cone 96 is still spaced slightly above end 52 of locking sleeve 46.

Fig. 14 illustrates the position of the parts at an instant later; that is, just as head-cone 96 first engages sleeve-end 52, it being noted that heads 99 are still within bore 63. At this time, finger-shoulders 100 are spaced vertically above barrel-shoulder 62 by a distance b. On the other hand, sleeve 46 must be moved downwardly a distance a, before groove 56 is brought into effective register with lock-balls 50. Distance a is measured between the center of a given ball i) when in the full-line, locking position of Fig. 14 and the center of curvature d of the arcuate shoulder 49 of sleeve 46, when said sleeve is in the locking position of Fig. 14, it being remembered that the radius of curvature of said shoulder is equal to the radius of a ball 50, as demonstrated by the dotted line circle 59a in said figure.

Upon further descent of tool F, finger-heads 99 descend through bore 63, and head-cone 96 depresses sleeve 46 against the action of spring 54, but distance a is purposely made to be less than distance b, so groove 56 will be brought into effective register with balis 50 before finger-shoulders 100 will have reached barrel shoulder 62. Therefore, it is assured that balls 50 will be freed for inward radial movement, to unlock barrel 17 from shoe C, before the fingers 98 can possibly efiectively latch the retrieving tool F to plug D. Accordingly, if the operator pulls up on the measuring line, mistakenly thinking the plug has been unlocked, the retrieving tool will merely pull clear of bore 63, and the retrieving operation must then be restarted. Were the retrieving tool to be latchable to the plug before the plug was unlocked from the shoe, the operator might haul up on line 79 before the unlocking had been accomplished, with consequent likelihood that the hoisting line would part.

However, as has been said, in the present case, groove 56 will be in eifective register with balls 50 some little time before shoulders 100 register with shoulder 62. When further descent of the retriever brings those shoulders into register, spring 102 will move collar 97 and fingers 98 downwardly, the heads 99 riding over cone and thus being positively radially projected (of course, their inherent spring-tendency is working in the same direction) until shoulders 100 underlie barrel-shoulders 62 (Fig. 15). Thus, retriever F is latched to plug D and when the measuring line is hauled in, lift will be imparted to the plug, spring 102 constantly keeping a relatively downward force on the fingers 98, and the cone 95 thus constantly forming a solid radial back-up for heads 99 so there may be no chance of the heads being cammed out of latching engagement with the barrel.

After the retriever has been latched to barrel 17 but before the measuring line has been hauled in, balls 50 will still occupy the full line positions of Fig. 15, though they are free to enter groove 56. And, of course, heads 99, in their engagement with shoulder 62 and cone 95, prevent upward movement of plunger 87 with respect to barrel 17, and head 94 thus holds sleeve 56 from moving upwardly under the influence of spring 54, even when the measuring line is hauled in. So, as the retrieving tool is raised, groove 56 remains in register with the balls 50 and, when the latter reach the shoulder 13 of the shoe-groove 12, said balls are cammed by that shoulder to the dotted line position of Fig. 15, thus unlocking plug D from shoe C. The plug is now lifted clear of the shoe and brought to the ground surface, whereupon it is freed from the retrieving tool and made ready for subsequent re-setting.

Various changes in design, structure and arrangement may be made without departing from the spirit and scope of the appended claims.

I claim:

1. In combination, a retrievable plug adapted to be set in a casing shoe and embodying a vertical, external barrel, an external packer on the barrel, locking detents carried by the barrel and movable radially to and from projected locking positions beyond the outer peripheral face of the barrel, a plunger within the barrel bore and mounted for limited axial movement, said plunger being operative, at' its upper limit of movement, so to project and hold the detents in locking positions, and, at its lower limit of axial movement, to permit the detents to move from locking positions, spring means holding said plunger in its uppermost position during descent of the plug to the shoe, and an annular shoulder within the bore of the barrel near its upper end, said shoulder inclining downwardly and outwardly and being spaced vertically above said plunger; and a setting tool latchable to and releasable from said barrel, said tool embodying a stem, a terminal head on the stem and engageable with the top of said plunger to depress it when the plug reaches the shoe, and a plurality of radially sprung fingers enterable in the topof the barrel bore and latchingly engageable with said shoulder.

2. The combination as in claim 1; wherein said head is spaced vertically below said fingers.

3. The combination as in claim 1; wherein said fingers include heads, and shoulders on the heads and complementary to said barrel shoulder.

4. In combination, a retrievable plug adapted to be set in a casing shoe and embodying a vertical, external barrel, an external packer on the barrel, locking detents carried by the barrel and movable radially to and from projected locking positions beyond the outer peripheral face of the barrel, a plunger within the barrel bore and mounted for limited axial movement, said plunger being operative, at its upper limit of movement, so to project and hold the detents in locking positions, and, at its lower limit of axial movement, to permit the detents to move from locking positions, spring means holding said plunger in its uppermost position during descent of the plug to the shoe, and an annular shoulder within the bore of the barrel near its upper end, said shoulder inclining downwardly and outwardly; and a retrievingtool latchable to said barrel, said tool embodying a body member, latching fingers on the body member and adapted to latchingly engage said shoulder, and a head on said body member and adapted to engage and depress said plunger, said fingers being movable into latching position only after the last mentioned head has depressed said plunger to its lower limit of movement.

5,. The combination as in claim 4; wherein said latching fingers are mounted for limited axial movement with respect to said last named head; and including a downwardly and outwardly tapering conical head-portion engaged by the free terminals of the fingers, and a spring urging said fingers downwardly with respect to said conical portion.

6. A retrievable plug adapted to be set in a casing shoe and embodying a vertical, external barrel, an external packer on said barrel, the barrel wall having radial ways extending therethrough, a plurality of balls, one in each way and each with a diameter greater than the thickness of the wall whereby the balls project radially from either or both sides of the wall in all their positions of movement, means on the barrel limiting the extent of radial outward movement of the balls, a plunger mounted within the barrel for limited axial reciprocation, spring means urging the plunger towards its upper limit of movement during descent of the plug to the shoe, a head on said plunger and located, when the plunger is at said upper limit, radially opposite and in engagement with the balls, said head being of substantially the same diameter as is the bore of the barrel whereby it holds said balls in positions of radial projection beyond the outer periphery of the external barrel, the plunger having an annular groove above the head, said groove registering with said balls when the plunger is at its lower limit of movement whereby said balls are then radially movable into the groove, the groove being of a depth to allow sufiicient ball-movement to accommodate the balls entirely within the groove and the ways without permitting the balls to leave the ways.

'7. In combination, a retrievable plug adapted to be set in a casing shoe and embodying a vertical, external barrel, an external packer on said barrel, the barrel wall having radial ways extending therethrough, a plurality of balls, one in each way and each with a diameter greater than the thickness of the wall whereby the balls project radially from either or both sides of the wall in all their positions of movement, means on the barrel limiting the extent of radialoutward movement of the balls, a plunger mounted within the barrel for limited axial-reciprocation, spring means urging the plunger towards its upper limit of movement during descent of the plug to the shoe, a head on said plunger and located, when the plunger is at said upper limit, radially opposite and in engagement with the balls, said head being of substantially the same diameter as is the bore of the barrel whereby it holds said balls in positions of radial projection beyond the outer periphery of the external barrel, the plunger having an annular groove above the head, said groove registering with said balls when the plunger is at its lower limit or movement whereby said balls are then radially movable into the groove, the groove being of a depth to allow sufiicient ball-movement'to accommodate the balls entirely within the groove and the ways without permitting the balls to leave the ways, and an internal annular and downwardly facing shoulder within the barrel bore at a point above said plunger; and a retrieving tool latchable to said barrel, said tool embodying a body member, latching fingers on the body member and adapted to latchingly engage said shoulder, and a head on said body member and adapted to engage and depress said plunger, said fingers being movable into latching position only after the last mentioned head has depressed said plunger to its lower limit of movement.

8. The combination as in claim 7; wherein said latching fingers are mounted for limited axial movement with respect to said last named head; and including a downwardly and outwardly tapering conical head-portion engaged by the free terminals of the fingers, and a spring urging said fingers downwardly with respect to conical portion.

9. A retrievable plug embodying a vertical barrel, an external packer on the barrel, locking detents carried by the barrel and movable radially to and from projected locking positions beyond the outer peripheral face of the barrel, a plunger within the barrel bore and mounted for limited axial movement, said plunger being operative, at its upper limit of movement to project and hold the detents in locking positions, and, at its lower limit of axial movement, to permit the detents to move from locking positions, and spring means holding said plunger in its uppermost position, said packer comprising a rigid collar and a ring of rubber molded to and extending below said collar, the lower face of the collar being provided with an annular groove of V cross section.

10. A plug as in claim 9, including also a second rigid collar on the barrel below the first mentioned collar and limited in its extent of upward movement theretowards, and a rigid, vertical and annular flange on the second collar and extending upwardly into said groove.

References Cited in the file of this patent UNITED STATES PATENTS 2,139,983 Stone Dec. 13, 19f8 2,297,044 Barker Sept. 29, 1942 2,355,854 Gean et a1. Aug. 15, 1944 2,401,119 Taylor May 28, 1946 2,409,811 Taylor et a1 Oct. 22, 1946 2,447,546 Spencer Aug. 28, 1948 

